More corrections re issue #1425
Rough draft of a new homepage; #1074

We've talked a lot about different ways to make the homepage dynamic.
Here I'm taking the opposite approach: this homepage is designed to
function primarily as a first impression of Gittip that answers the most
basic questions, and then leads people in one of three further
directions: signing up, browsing communities, or reading about Gittip.
Let's make the community and profile pages the focus of dynamic activity
on the site, not the homepage.
Use a single penny bg + color overlays

This ensures that pennies line up from block to block.
Merge branch 'master' into new-homepage
Shelve
Merge branch 'master' into new-homepage
Homepage is pretty presentable. Homestretch!
Make new homepage responsive
Tweak verbiage for browsing communities
Responsiveness tweaks
Fix up test suite
Merge branch 'master' into new-homepage
Tweak site description in a couple places

Use the verbiage we're now using on the homepage.
Remove old thing from homepage
Fix sign-in on inside pages
Here's a very basic authenticated homepage
Redirect to profile page from homepage sign-in

`/about/me//` is a hack to work around bugs in Aspen wildfile handling.
Prune an extra CSS definition
Fix homepage on Firefox
Add Sign Out link on authenticated homepage